Method and apparatus for the liquid treating of fiber tow bundles



Jan. 22, 1963 c. F. OLDERSHAW 3,074,775

METHOD AND APPARATUS FOR THE LIQUID TREATING 0F FIBER TOW BUNDLES FiledSept. 13, 1957 2 Sheets-Sheet 1 I A A w 147 T ORA/5 Y5 Jan. 22, 1963 c.F. OLDERSHAW 3,074,775

METHOD AND APPARATUS FOR THE LIQUID TREATING 0F FIBER TOW BUNDLES FiledSept. 13, 1957 2 Sheets-Sheet 2 Z2 19 I F 25 l 50 his 25 51 INVENTOR.Char/9.5 F. U/C/W'S/IO'W HTTOR/VA'YS In the manufacture of many of theso-called artificial silks and textile and other fibers from othermanmade, synthetic, fiber-forming materials, it is oftentimes requiredto wash out or extract certain undesired constituents and impurties'from the freshly spun filamentary products in order to provide them in asatisfactorily useful and commercially acceptable form. Wet spun yarnsand filaments, for example, must generally be washed in a suitableextractant medium or washing liquid (that frequently may be water or anaqueous liquid) in order to remove residual quantities of the spinningsolution solvent that was employed to furnish the fiber-forming materialin extrudable form, as well as any coagulant that may persist in thefreshly spun andnewly formed fiber by entrapment or entrainment afterits withdrawal from the coagulating spin bath. Certain of the artificialand synthetic textile fibers that are prepared by dry or evaporativespinning techniques may also require washing for similar purposessubsequent to their extrusion. Likewise, some of the melt spun syntheticfilamentary materials may need to be washed after being spun. Thus,certain of the superpolyamide fibers, particularly, by way ofillustration, those that are derived from the epsilon-caprolactam (whichare sometimes popularly known as being nylon 6-type materials), mustusually be washed after spinning in order to be rid of intolerably highcontents of monomer and undesirably loW molecular weight polymer,including dimer and trimer, that invariably obtains in the freshlyextruded material.

For purposes of washing and otherwise processing many synthetic andartificial textile fiber materials subsequent to spinning, it is usuallyconvenient and expedient to form the fibers in continuous or endlessfilamentary lengths that, during orsubsequent to spinning, are assembledin multiple filament tow bundle arrays or gathered arrangements in whicha plurality of individual, component continuous filaments are handled ina closely associated, substantially parallel relationship. This isparticularly the case for many of the wet spun synthetic textilematerials, including those that are derived from fiber-formingacrylonitrile polymer compositions, particularly polyacrylonitrile andcopolymers that contain in the polymer molecule at least 80 percent orso by weight of acrylonitrile. In many such operations, notably those inwhich relatively fine denier textile fiber products are beingmanufactured for ultimate conversion into staple fiber commodities, itis desirable for such multiple filament tow bundles to be ofconsiderable magnitude. Often, for example, in the manufacture of say, 1to 10 denier products, it may be preferred to operate with tow bundlesthat, quite commonly, are comprised of from 10,000 to 50,000 or moreindividual, filaments. As a practical matter, it is frequently preferredto form and handle such ponderous tow bundles as relatively flat andwide, ribbon-like arrays that have characteristically rectangularcross-sections with an average depth or thickness which, as a practicalmatter, is usually at least about 40 or so filaments and seldom inexcess of 125 or so filaments. Of course, if desired, much thinner towbundles can also be utilized such as those whose average thickness is onthe order of, say, only 5 to filaments. Physical arrangements of suchnature for the tow bundle provide for greater facility in itsmanipulation during processing. And, in connection with tes Patent 03,074,775 Patented Jan. 22, 1963 the washing and liquid treatment ofsuch tow bundles, it is usually preferred to employ countercurrentliquid contacting techniques and processing schemes in which thedirection of travel of the tow through one or more stages is oppositethe path of flow of the washing or treating liquid that is beingemployed. This, as is widely recognized, generally secures optimumefiiciency in the operation. In this connection, maximum benefit isusually obtained in such liquid treatments when plural, separate stagewashing or other liquid treating appliances are employed and the towbundle being passed through the stages is actually physically lifted outof One stage (or container therefor) for transfer into the next by meansof guide bars, rollers and the like devices well known to the art.

The main purpose and chief concern of the present invention is toprovide an improved method and highly effective apparatus for use inconjunction therewith for washing or leaching extractable constituentsfrom various artificial and synthetic textile fiber materials duringtheir processing in the form of multiple continuous filament tow bundlessubsequent to spinning, especially tow bundles that have a relativelyfiat, ribbon-like form and are filamentary gatherings of considerablemagnitude. It is a particular object and specific relationship of theinvention to deal with the washing of wet spun synthetic textilematerials, especially fibers from acrylonitrile polymer compositionsthat are obtained and handled in an aquagel form upon their spinning andduring their immediately subsequent handling which occurs prior todrying. As is well known, such aquagel materials are the waterswollen orhydrated filamentary structures that may be derived by wet spinningextrudable solutions of acrylonitrile polymers inpolyacrylonitrile-dissolving aqueous saline solvents (that beneficiallymay be Zinc chloride and its saline equivalents for such purpose) intoaqueous, non-polymer-dissolving coagulating spin bath solutions of thesame salt or salts. A highly important purpose of the invention, one ofparticular significance and which is calculated to provide exceptionaladvantage, is to furnish a method and means of the indicated variety foruse in plural stage liquid treatments that would secure improvedseparation of the stages and permit plural stages to be built moreeconomically, operated with relatively less expense and maintained with.minimized requirements for physical space. And, as can readily becomprehended by those who are gifted with the skill of their calling,the broader aspects of the present invention include an improved processand apparatus for any liquid treatment upon any filamentary textilematerial, including those of natural origin, wherein it may be desiredto handle the filaments in a tow-like form (including roving andsliverlike assemblies), especially as a large, ribbon-like tow bundle,for countercurrent passage through a particular desired beneficialtreating liquid.

According to the present invention, wherein the abovestated ends and theindicated and corollary benefits may most advantageously be achieved, atow-bundle or like arrangement of continuous filament fibers, especiallya relatively large array of considerable magnitude in a fiat,ribbon-like assembly, may be washed free or substantially free fromundesired, liquid extractable, constituent impurities or otherwisetreated in and with a beneficial treating liquid by a method which, on acontinuously operating basis, comprises introducing said multiplecontinuous filament tow bundle into a countercurrently flowing treatingliquid in a first liquid treating stage at one end of a bath of desiredtreating liquid that consists of a plurality of at least two physicallyseparated but intercommunicating stages; passing said tow bundle in asequential fashion through said counter-currently flowing treatingliquid in each of said stages; withdrawing the liquid treated tow bundlefrom said treating liquid in the last of said stages at the opposite endof said bath; introducing or admitting at least a portion of freshtreating liquid in the last of said stages; withdrawing at least aportion of the spent or used treating liquid from the first of saidstages; and passing said treating liquid from the last of said stages tothe first thereof through each of said stages countercurrent to said towbundle in such a manner that, at (or about at) each point of physicalseparation or compartmentation between each of said stages, saidcountercurrently flowing treating liquid is caused to pass and flowthrough and between the integrant filaments in said tow bundle that istraversing (and while it is traversing) said point of separation.

Advantageously, as has been indicated, the tow bundle may be aribbon-like array of considerable magnitude that contains a largeplurality of the individual filaments that are desired to be treated.Desirably, the filaments may be freshly spun, especially freshly wetspun filaments, of synthetic or artificial textile fibers that are beingwashed for their purification from solvents, coagulants and other liquidextractable contaminants subsequent to their formation. It is highlybeneficial to water wash freshly wet spun tow bundles of acrylonitrilepolymer aquagel filaments that contain solvent (and possibly coagulant)residues of an aqueous saline nature which persist in the filamentsafter their withdrawal from the spin bath. It is usually preferable topractice the invention with a bath of the beneficial treating liquidthat is compartmentalized or physically separated into at least 2 and,more advantageously, at least 4 or even 10, individual stages whereinall or substantially all of the fresh treating liquid is admitted to thelast stage for counter-current flow through the bath and whereinsubstantially all of the spent or used treating liquid is withdrawn oremptied through and from the first stage. Of course, the precise numberof stages that may be best to employ in any particular situation dependsto a great extent on the particular operation and liquid treatmentinvolved and the efiiciency or results desired in its performance.Almost inevitably, regard-less of the number of stages used, some of thetreating liquid will be entrained in the tow bundle and carried oiftherewith upon its withdrawal from the baths. Preferably the bath iscontained in an open, horizontally disposed pan or trough although, ifdesired, totally enclosed chambers in other than horizontal dispositionmay be employed. As is apparent, any desired portion of the treatingliquid can be admitted or withdrawn, if so desired, at one or more ofthe intermediate stages of the bath when more than two are involved.Such procedure, however, is ordinarily of lesser attractiveness thanthat which involves admission of all the treating liquid in the laststage and withdrawal of substantially all of it in the first.

The particular rates of passage of the tow bundle through the bath andof the liquid into and out of the bath and the relative ratios oftreating liquids to tow that are being employed depend largely upon andmay vary with individual circumstances. Greater volumes of treatingliquid, especially for washing, generally bring about most eflicacioustreatments. However, an economic balance must be struck so thatemployment of excessive quantities of liquid are avoided. Likewise, theflushing and contacting action of the liquid on the tow must not be sovigorous as to cause damage to the individual filaments therein,especially when freshly wet spun filaments are involved. Such filaments,particularly aquagel structures of acrylonitrile polymers, may be quitetender and easily susceptible to damage. As is ordinarily considereddesirable, particularly in washing and liquid extraction operations, thetreating liquid upon withdrawal from the bath has generally mosteffectively been employed when it is in a completely utilized conditionin which it retains little if any beneficial treating potency for theparticular purpose at hand. In washing operations, thiscondition isgenerally brought about for the reason that the used treating liquid issubstantially at equilibrium with respect to its solute-attractingpotency with the untreated fibers. It is deemed that the mostsatisfactory arrangements and mode of operation for practice of theinvention in particular instances and for particular purposes can beeasily determined and arrived at by those who are skilled in the art andthat, in general, no more than routine experimentation in the light anddirection of the present contribution need be resorted to to attain suchend.

The apparatus of the invention in its most basic and generic conceptcomprises a means for containing a bath of treating liquid; partitionmeans in said bath containing means for subdividing it into a sequentialplurality of at least two stages; each of said partition means beingprovided with a tow-bundle-accommodating opening or aperture that isadapted to fit closely about and permit the passage of a multiplecontinuous filament tow bundle in submersion in said bath (when said towbundle and said bath are present in and being passed through saidcontaining means for said bath) from stage to stage, said opening beingfurther adapted to provide liquid communication between said stages;means for passing a tow bundle sequentially through each of the saidstages from the first to the last thereof through said partitionopenings; and means for circulating treating liquid for said tow bundlethrough said partition openings and, coincident thereto, through each ofsaid stages in said bath countercurrent to the path of travel of saidtow bundle. The most advantageous embodiment of the apparatus that is tobe used for any particular purpose may be collated to and based upon themost desirable manner for performing the particular method or treatmentwhose practice it is designed to afford. Thus, as will hereinafterappear, the apparatus may quite beneficially be a horizontally disposed,relatively flat or shallow pan or trough having a plurality of wall-likepartitions spaced at about regular longitudinal intervals, each of whichpartitions has a substantially rectangular, slit-like opening below theintended liquid level of the bath to accommodate passage of thepreferred form of ribbon-like tow bundle. Of course, apertures havingother configurations, such as circular or elliptic shapes, may beprovided in the partitions to conform to tow-bundles having other thansubstantially rectangular cross-sections. In addition, it is ofexceptional benefit for the upper portion of the partition to be offsetfrom its lower section surrounding the tow-accommodating aperture so asto cause a substantially vertical interpassage of the treating liquidthrough the tow bundle at each of the points of physical stageseparation. Furthermore, it is highly desirable for the upper portion ofeach partition to be removably provided in the apparatus and for each ofthem to be movably mounted therein so as, under the influence ofgravity, to ride upon and firmly enclose or confine the tow bundlepassing through the opening in the partition. Preferably, the entireplural stage unit is longitudinally tilted, inclined, sequentiallystepped or otherwise provided so as to permit gravity flow of thetreating liquid through the apparatus. To this end, especially whenaqueous treating liquids are involved, it is desirable for the gravityflow to be caused by the pressure effect of about a half-inch of waterhead differential between each of the successive, interconnected stagesin the assembly.

It is highly advantageous, especially if maximum washing elficiency isdesired, to include in some and preferably all of the stages some meansfor physically agitating the tow bundle in the treating liquid or oftransversely flushing the tow bundle with some portion of thecountercurrently passing liquid.

Practice of the present invention intrinsically provides for andaccomplishes many real and very worthwhile advantages and benefits. Asis apparent, it neatly achieves a basic requirement for optimum resultsin countercurrent liquid treating processes 'of separating the treatingbath into consecutive, individual stages. This is done with utmosteconomy in requirements for materials, apparatus and space. At the sametime, it secures a unique and most effective flushing or intimatecontacting action of the treating liquid passing through the tow bundleat each of the stage separating partitions. This is effected by means ofan extremely simple apparatus with minimized propensity for back mixingto occur between the liquid constituents of the various stages whilesimultaneously avoiding and eliminating any necessity for using rollers,guides or other means to physically withdraw the tow out of a firststage for transfer to and reintroduction in the liquid of a subsequentcountercurrent stage. Great economies in tow handling apparatus are, ofcourse, thereby made possible, as well as in requirements for plural,individual installments of liquid containing devices. Likewise,performance of the liquid treatment may be accomplished on a basis ofminimum operating cost. Furthermore, the present invention permitssubstantial reductions in the length of a given treating bath to be madewhen it is practiced in conjunction with tow agitating or transverseflushing means in the stages, due to the greater liquid treatingefficiency that it involves as compared with continuous undivided bathsor even plural stage baths of sequential, individually contained liquidvolumes. Frequently as much as -50 percent and even much greaterreduction in length of a liquid treating bath 7 may be achieved when thepresent invention is utilized in the last mentioned way so as to agitateor flush the tow being treated in preference to conventional liquid 7treating or wash bath installations. I

In the several views of the accompanying drawing wherein, insofar as maybe possible, like reference numerals refer to like parts or components,there are illustrated certain of the preferred embodiments of theinvention that are not intended to be limiting or restrictive thereofbut which are included herewith for purposes of convenient illustration.As shown;

FIGURE 1 is a fragmentarly plan view of an apparatus according to theinvention;

FIGURE 2 is a side elevation in section taken along the line 2-2 inFIGURE 1;

FIGURE 3 is a simplified schematic representation presented in crosssection which shows a four stage liquid treating bath according to theinvention in operation with a tow bundle passing therethrough;

FIGURE 4 is a fragmentary plan view of a preferred form ofstage-separating partition means for use in the practice of theinvention;

FIGURE 5 is a front elevation of the partition, partly in section, takenalong the line 55 in FIGURE 4;

FIGURE 6 is a side elevation in section taken along the line 6-6 inFlGURE 4; and

FIGURES 7 and 8, which are both fragmentary front elevations in section,schematically depict tow bundle agitating and transverse liquid flushingarrangements, respectively, which may be used in conjunction with thestage separating means in the practice of the present invention.

With initial reference to FIGURES l and 2 of the drawing, there is showna pan or trough 7 for containing a bath of beneficial treating liquidfor a tow bundle of fibers (neither of which are shown in the first twofigures') to be passed through the bath when it is contained in thetrough and caused to flow countercurrent to the tow bundle. The trough7, which may be of any desired or necessary length, width and depth, isdivided into a plurality of intercommunicating liquid-containing stages8 by a plurality of partitions or aperture-containing wall members 9. Asindicated, and as is shown in FIGURE 2, each of the partition members 9is provided with an opening or aperture 10 that is adapted to fitclosely abouta tow bundle being passed through the multiple stage bathWhile providing means for permitting the countercurrent flow of treatingliquid through the stages 8 in the trough -'1. As has been mentioned,the openings 10 in the part1- tion 9 may haveany configuration capableof best accommodating the shape of a particular tow bundle beinghandled. Quite advantageously, the openings 10 may be substantiallyrectangular to match a flat, ribbon-like tow bundle of continuousfilament fibers so as to facilitate the handling of the tow bundle insuch form. The openings 10 are formed or provided in the partitions 9 ata level beneath the intended liquid level of the treating bath so thatthe tow bundle can be passed completely through all of the stages in thebath while remaining in complete submersion therein during suchmanipulation.

An embodiment of the method of the present invention with an apparatusin accordance therewith is schematically portrayed in FIGURE 3. Thetreating bath is divided into four equal stages 8 that are separated bythe partitions 9. Advantageously the treating bath may be a bath ofaqueous wash liquid 15 for a multiple continuous filament tow bundle 11of freshly wet spun polyacrylonitrile filaments in aquagel form thathave been withdrawn from a coagulating bath therefor (not shown) andwhich contain residual quantities of an aqueous saline solution thatremains primarily from the solvent and which must be washed out of thefilaments to provide them in a suitable physical form and commerciallyacceptable condition. The tow bundle 11 is introduced into the treatingliquid 15 in the first stage of the bath by being passed under a rollerguide 12 or equivalent tow-handling and forwarding means for thepurpose. The tow bundle 11, as has been indicated, is advantageouslyassembled as a relatively flat, ribbon-like array of individualcontinuous filaments having a substantially rectangular cross-section.The tow bundle 11 is sequentially passed through all of the stages inthe bath; traversing each of the stage-separating partition members 9through the tow-accommodating apertures 10 therein. The tow bundle 11 iswithdrawn from the last stage of the treating bath around the rollerguide 13 after having been thoroughly washed or otherwise treated. Thetreating liquid 15 which, as indicated, may advantageously be an aqueousliquid for washing purposes, is passed countercurrently through each ofthe stages of the bath against the tow bundle. Preferably, this is doneby gravity flow, as has been indicated, through stepped or inclinedstages. If desired, however, the liquid can actually be pumped throughthe stages by any suitable fiuid-impelling means. The treating liquid 15is admitted in the last stage of the bath through the liquid inlet 14and is withdrawn in a spent or used condition after its countercurrentflow from the first stage of the bath through the liquid outlet 16.

In passing from stage to stage in the bath, thetreating liquid passesthrough the apertures or openings 10 in the partition members 9 directlythrough and between the individual filaments in the tow bundle 11 whilethe filaments are traversing each of the partitions in their move mentfrom stage to stage. This, as has been indicated, secures a highlyefficient flushing and washing action or other liquid treating contactof the liquid 15 on the tow bundle 11. It is possible, incidentally, tooperate in such 0 a manner that some of the liquid overflows thepartitions.

..Preferably, however, all or substantially all of the liquid is passedthrough the openings 10 in the partitions 9 so as to actually traversethe tow bundle in its interstage movement.

When acrylonitrile polymer aquagel filament tow bundles are being washedfrom residual quantities of the spinning solution solvent after havingbeen withdrawn from the coagulating spin bath, it is generally desirableto countercurrently pass at'least about 7 parts by weight of the washliquid, that preferably is introduced as fresh water in the last stage,for each part by weight of the polymer (on a dry weight basis) that iscontained in the aquagel filaments. Frequently, it may be preferable toemploy from 8 to 40 parts by weight of aqueous Wash liquid for eachpartby weight of polymer in the tow bundle. In

connection with this, when acrylonitrile polymer filaments are wet spunin aqueous saline solvents using aqueous saline coagulants, the freshlyspun filaments generally contain at least about parts by weight of saltsolution to each part by weight of polymer therein, which solutionusually has at least about 45 percent by Weight of zinc chloride or itssaline equivalents. Such filaments must ordinarily be washed to acondition in which they contain not more than about 0.5 percent byweight of salt, preferably less than about 0.1 percent by weight, basedon the dry weight of the polymer in the filaments. A thoroughly washedtow of aquagel filaments generally contains about 4 parts of water perpart by Weight of dry polymer. In the wash liquid that is employed incountercurrent washing processes for such aquagel filaments, it isusually desirable to employ the liquid to such an extent in the washingprocess that the spent or used liquid that is withdrawn from the firststage of the treating bath contains at least about percent by weight ofsalt that has been extracted from the aquagel filaments and preferablyat least about 30 or 50 percent by weight of salt, especially when it iszinc chloride.

One possible embodiment of a preferred form of partition member orweir-like stage separatoris shown in FIGURES 4, 5, and 6 of the drawing.The partition 9 is comprised of upper and lower sections or members 19and 20, respectively. The lower member 20 may be securely fixed ormounted at the bottom of the trough 7. The upper member 19 mayadvantageously be removably installed in the trough in such a mannerthat it is slida-bly disposed across the width of the trough so as topress closely on and fit accurately with the tow bundle that is passingthrough the opening it) in the separator or partition 9. This may bereadily accomplished, as is shown, by mounting the upper partitionmember 19 in a groove, permitting it to be easily removable andachieving the desired slidable disposition in the assembly. Thus, as isshown in FIGURES 4 and 6, the upper partition member is held between thegrooves 21 in the trough. Advantageously the grooves may be provided inmounting elements that are arranged in a suitable disposition. As shown,the upper partition member may actually consist of two slit-likesections which each extend inwardly from the sides of the trough to acentrally provided mounting element 25 that is grooved on each side tomatch the grooves in the mounting elements near the side walls of thetrough. The central mounting element, of course, temporarily divides thetow bundle in its passage through the partition. Such an arrangementfacilitates transverse division or separation of very wide tow bundlesfor ease in handling through certain arrangements. Use of centrallydividing mounting elements is not at all necessary and, quitefrequently, can be avoided with complete satisfaction.

In addition, as shown, several matched grooves may be provided in eachof the mounting elements to facilitate changes in the spacing betweenthe upper and lower members of the partition. These are shown as thegrooves 22 and 23 which are provided adjacent to the grooves 21 in whichthe upper partition member is mounted. As has been indicated, it isbeneficial for the upper portion of the partition to be longitudinallyoffset from the lower section surrounding the tow accommodatingaperture. Such an arrangement is apt to secure the desirablesubstantially vertical interpassage of the treating liquid through thetow bundle at each of the points of physical stage separation. Theoffset arrangement between the upper and lower partition members mayadvantageously be such that the upper member 19 is spaced from the lowermember 20 in the same direction as the direction of travel of tow bundlethat is passing through the assembly in the bath, as is indicated by thearrow 30. This, of course, is opposite to the path of thecountercurrently flowing treating liquid, as is indicated by thedirectional arrow 31. In such an assembly a countercurrent treatingliquid passes through the tow bundle in the opening 10 of the partitionsubstantially in the direction of the arrow 32 that is drawn in FIGURE6.

Of course, if it should be desired, the upper partition member ormembers 1? may be spaced and offset from the lower member 20, on theupstream side of the partition with respect to the fiow of treatingliquid. When such an arrangement is made, the treating liquid passesdown through the tow bundle in a generally downward manner rather thanup through the assembled filaments in the manner of flow that isillustrated in FIGURE 6.

In FIGURE 7, there is schematically illustrated a means for agitatingthe tow bundle 11 during its passage through one of the stages in orderto increase the liquid treating efiiciency of the operation beingperformed and to secure maximum benefit in the practice of the presentinvention. To this end and pursuant to such practice, any suitable meansfor vertically reciprocating or agitating the tow bundle 11, such as thereciprocating element 40 which is vertically operable (as indicated bythe bidirectional arrow), may be employed in order to reciprocate thetow bundle and move it back and forth between spaced upper and lowerlimits, such as the points designated by the arrows U and D,respectively. Advantageously, the means that is employed for suchpurpose may be in essential accordance with that which has beendisclosed in the copending application for United States Letters Patenthaving Serial No. 663,694, which was filed on June 5, 1957, by Thomas C.Spence, Rex E. Thomas, and Arthur B. Greenwood for a Method andApparatus for Washing Tow Bundles of Wet Spun Fibers.

Another advantageous means forgreatly increasing the efiiciency of theliquid treatment on the tow bundle which may be achieved in any or allof the stages in the practice of the present invention is in keepingwith the manner that is schematically illustrated in FIGURE 8, wherein ameans is utilized for transversely flushing the tow bundle with aportion of the treating liquid being passed through the stage.Preferably, the portion of the liquid that is employed for thetransverse flushing is internally circulated from the volume of thetreating bath that is contained within each stage. The recirculatedliquid is passed through a liquid distributor or ejecting elementadjacent to the tow bundle 11, such as the element 45, which isschematically depicted in FIGURE 8. Most advantageously, the distributorelement 45 is adapted to pass a sheet-like stream of the recirculatedtreating liquid transversely through the passing tow bundle so as tosecure an effective flushing action therethrough in the generaldirection indicated by the arrows 50. Most advantageously, the flushingor transverse washing means that is utilized is embodied and employed inaccordance with the disclosure of the copending application for UnitedStates Letters Patent having Serial No. 683,653, which was filed onSeptember 12, 1957, by Charles F. Oldershaw for an improvement inTreating Tow Bundles With Beneficial Liquids.

As has been mentioned, the treating liquid 15 that is employed may be ofany desired variety that may be utilized for accomplishing a beneficialefiect upon the fibers. While it is of great advantage, as is apparent,to wash freshly spun articles and synthetic fibers in the practice ofthe technique and with physical means according to the invention, otherbeneficial liquid treatments on textile fibers of practically anydesired origin may also be achieved. Thus the fibers may be bleached,scoured, dyed, lubricated, conditioned or provided with coatings orfinsh deposits of various sorts from diverse types of liquid applicatingcompositions in the practice of the invention. Other suitable liquidtreatments may also be done in this manner.

By way of further illustration, an apparatus patterned after that shownin FIGURE 3, but having stage separating partition elements similar tothose shown in FIGURES 4, 5 and 6, is employed to wash a freshly wetspun tow bundle of polyacrylonitrile aquagel filaments that consists ofabout sixty thousand individual continuous filaments, each of which hasan ultimate denier, as a finally finished textile fiber product, ofabout three. Upon their introduction into the treating liquid, theaquagel filaments contain about parts by weight of 45 percent by weightaqueous zinc chloride solution to each part by weight of polymer (on adry basis) therein.

The wash bath has a total length of about 70 feet, a width of about 1.5feet and is adapted to contain the wash liquid at an average depth ofabout 3 inches. The stage separating partition elements in the bath areseparated at about 3.5 feet intervals. The upper partition memberssurrounding the openings in each of the stage separators have anefiective vertical width of about 1.25 inches in the treating bath andare offset, or are spaced downstream with respect to the wash liquidfrom the lower partition members, by a distance of about 1.5 inches. Thelower partition members in each of the separators are rectangular wallsthat extend upwardly about 1.75 inches from the bottom of the trough.This, in effect, provides a substantially rectangular opening in each ofthe partition members that lies disposed in a horizontal plane so as toaccommodate passage of the tow through the partition in a sort ofzig-zag manner of progression. The tow widthaccommodating length of eachopening in each partition member is about 12 inches. The apparentcross-section dimensions of the tow are about 0.22 by 12 inches, so thatit closely conforms to the openings in the partition members during itszig-zag passage between the stages.

The tow is passed through the bath at a linear rate of about feet perminute. Fresh water is introduced in the last stage of the bath at arate of about 1.7 gallons per minute and passed countercurrent to thetow bundle through each of the stages to be withdrawn from the firststage containing about 31 percent by weight of zinc chloride. The washedtow contains about 4 parts by weight of water to each part by weight ofpolymer. It has an excellently low salt content, based on the weight ofthe polymer therein, of about 0.1 percent. The Washed tow, uponwithdrawal from the bath, is subsequently dried. It provides premiumquality, polyacrylonitrile textile fiber products.

The efliciency of the above-described washing operation can be greatlyincreased and the requisite length of the wash bath considerably reducedby employing in each stage either physical tow agitating means such asis illustrated in FIGURE 7 of the drawing (especially when they are inaccordance with those described in the referred-to copending applicationof Spence, Thomas and Greenwood) or transverse liquid flushing means(particularly of the type comprehended in the referred-to copendingapplication of Oldershaw), or both, if such a dual installation is sodesired.

What is claimed is:

1. A method for treating a tow bundle of a plurality of continuousfilament fibers which comprises, on a continuously operating basis,introducing said multiple continuous filament tow bundle into acountercurrently flowing treating liquid in a first liquid treatingstage at one end of a bath of said treating liquid that consists of aplurality of at least two physically separated stages each sequentiallyintercommunicating through an opening at the point of physicalseparation between each stage which opening is adapted to fit closelyabout and permit the substantially squeezeless passage therethrough ofsaid tow bundle while permitting liquid communication between adjacentstages through said opening and the tow bundle therein; passing said towbundle in a sequential fashion through each of said openings and throughsaid countercurrently flowing treating liquid in each of said stages sothat said tow bundle, without being substantially squeezed therein,fills each opening through which sequential stages intercomrnunicate ateach point of physical separation between stages; withdrawing the liquidtreated tow bundle from said treating liquid in the last of said stagesat the opposite end of said bath; admitting at least a portion of freshtreating liquid in the last of said stages; withdrawing at least aportion of the used treating liquid from the first of said stages; andpassing said treating liquid from the last of said stages to the firstthereof through each of said stages, countercurrent to said tow bundle,in such a manner that at each point of physical separation between eachof said stages, all of said countercurrently flowing treating liquidflowing through the opening from stage to stage is caused to pass andflow through and between the integrant filaments in said tow bundle, asaforesaid, filling said opening in a substantially squeezeless mannerwhile said tow bundle is transversing said point of separation.

2. The method of claim 1, wherein the tow bundle is comprised of freshlywet spun filaments containing residual impurities and said treatingliquid is a washing liquid for extracting said impurities.

3. A method in accordance with the method that is set forth in claim 1,and including the additional step in integral combination therewith ofphysically agitating said tow bundle in a relatively vertical up anddown manner within said treating liquid while it is passing through oneor more of said stages.

4. A method in accordance with the method that is set forth in claim 1,and including the additional step in integral combination therewith oftransversely flushing said tow bundle with said treating liquid while itis intermediate between and passing through one or more of said stages.

5. The method of claim 1, wherein said treating liquid is passed throughsaid stages by gravity flow.

6. The method of claim 1, wherein said tow bundle is com-prised of atleast ten thousand individual filaments and is assembled in asubstantially flat, ribbon-like form.

7. A method in accordance with the method that is set forth in claim 6,wherein the average thickness of said tow bundle is between about 5 andfilaments.

8. A method in accordance with the method that is set forth in claim 7,wherein the average thickness of said tow bundle is at least about 40filaments.

9. The method of claim 1, wherein the tow bundle is comprised of freshlywet spun acrylonitrile polymer aquagel fibers and wherein said treatingliquid is water.

10. A method in accordance with the method that is set forth in claim 9,wherein between about 8 and 40 parts by weight of water are employed forwashing each part by weight of polymer on a dry basis and said towbundle.

11. A method in accordance with the method that is set torth in claim10, wherein at least 4 individual stages are employed in said wash bath.

12. A method in accordance with the method that is set forth in claim10, wherein all of the water is admitted in the last of said stages andsubstantially all of the used washed liquid is withdrawn from the firstof said stages.

References Cited in the file of this patent UNITED STATES PATENTS1,175,538 Matos Mar. 14, 1916 2,131,409 Nai Sept. 27, 1938 2,133,535Campolunghi Oct. 18, 1938 2,149,708 Von Recklinghausen Mar. 7, 19392,772,552 Nikles Dec. 4, 1956 2,782,623 Coe Feb. 26, 1957 2,949,337Oldershaw Aug. 16, 1960 FOREIGN PATENTS 460,079 Great Britain Jan. 20,1937

1. A METHOD FOR TREATING A TOW BUNDLE OF A PLURALITY OF CONTINUOUSFILAMENT FIBRES WHICH COMPRISES, ON A CONTINUOUSLY OPERATING BASIS,INTRODUCING SAID MULTIPLE CONTINTUOUS FILAMENT TOW BUNDLE INTO ACONTERCURRENTLY FLOWING TREATING LIQUID IN A FIRST LIQUID TREATING STAGEAT ONE END OF A BATH OF SAID TREATING LIQUID THAT CONSISTS OF APLURALITY OF AT LEAST TWO PHYSICALLY SEPARATED STAGES EACH SEQUENTIALLYINTERCOMMUNICATING THROUGH AN OPENING AT THE POINT OF PHYSICALSEPERATION BETWEEN EACH STAGE WHICH OPENING IS ADAPTED TO FIT CLOSELYABOUT AND PERMIT THE SUBSTANTIALLY SQUEEZELESS PASSAGE THERETHROUGH OFSAID TOW BUNDLE WHILE PERMITTING LIQUID COMMUNICATION BETWEEN ADJACENTSTAGES THROUGH SAID OPERATINGS AND THE TOW BUNDLE THEREIN; PASSING SAIDTOW BUNDLE IN A SEQUENTIAL FASION THROUGH EACH OF SAID OPENINGS ANDTHROUGH SAID COUNTERCURRENTLY FLOWING TREATING LIQUID IN EACH OF SAIDSTAGE TO THAT SAID TOW BUNDLE, WITHOUT BEING SUBSTNTIALLY STAGESTHEREIN, FILLS EACH OPENING THROUGH WHICH SEQUENTIAL STAGESINTERCOMMUNICATE AT EACH POINT OF PHYSICAL SEPERATION BETWEEN STAGES;WITHDRAWING THE LIQUID TREATED TOW BUNDLE FROM SAID TREATING LIQUID INTHE LAST OF SAID STAGE AT THE OPOSITE END OF SAID BATH; ADMITTING ATLEAST A PORTION OF FRESH TREATING LIQUID IN THE LEAST OF SAID STAGES;WITHDRAWING AT LEAST A PORTIION OF THE USED TREATINGG LIQUID FROM THEFIRST OF SAID STAGES; AND PASSING SAID TREATING LIQUID FROM THE LAST OFSAID STAGES TO THE FIRST THEREOF THROUGH EACH OF SAID STAGES,COUNTERCURRENT TO SAID TOW BUNDLE, IN SUCH A MANNER THAT AT EACH POINTOF PHYSICAL SEPARATION BETWEEN EACH OF SAID STAGES, ALL OF SAIDCOUNTERCURRENTLY FLOWING TREATING LIQUID FLOWING THROUGH THE OPENINGFROM STAGE TO STAGE IS CAUSED TO PASS AND FLOW THROUGH AND BETWEEN THEINTEGRANT FILAMENTS IN SAID TOW BUNDLE, AS AFORESAID, FILLING SAIDOPENING IN A SUBSTANTIALLY SQUEEZELESS MANNER WHILE SAID TOW BUNDLE ISTRANSVERSING SAID POINT OF SEPARATION.